Method for drilling through cavities during earth drilling operations

ABSTRACT

A method of bridging cavities encountered during drilling of bore holes in the earth by ceasing the drilling operation, lowering a bridging means of a plurality of rods or tubes fixed together at their upper and lower ends in the shape of a cylindrical cage down the borehole until extends across the cavity from the borehole to at least the bottom of the cavity and pouring concrete down the borehole forming a column thereof across the cavity in alignment with the bore hole, allowing the concrete to set and then resuming the drilling operation.

United States Patent [1 1 Mackie I 1 Oct. 28, 1975 METHOD FOR DRILLING THROUGH CAVITIES DURING EARTH DRILLING OPERATIONS William Duncan Mackie, c/o Fluor, C.C.S. Camp, Mount Tom Price, Australia Filed: Oct. 12, 1973 Appl. No.: 405,738

Inventor:

US. Cl. 166/287; 166/243; 166/285; 175/72 Int. Cl. E21B 33/13 Field of Search 61/53.66, 72.2; 166/117, 166/162, 169, 234, 241, 285, 286, 287, 243, 277, 280, 281, 283, 289, 290, 291, 205, 227, 315; 175/72; 264/35 References Cited UNITED STATES PATENTS Burgher 166/290 166/286 2,286,835 6/1942 Robinson et a1 166/295 2,387,493 10/1945 Brokaw 166/241 2,708,973 5/1955 Twining 166/285 2,800,185 7/1957 Teplitz.... 166/290 3,289,761 12/1966 Smith et al.. 166/290 3,481,402 12/1969 Beckett 166/290 3,555,689 1/1971 Cubberly 166/241 Primary Examiner-Stephen J. Novosad Assistant Examiner-Jack E. Ebel Attorney, Agent, or F irmUlle C. Linton [5 7 ABSTRACT 3 Claims, 5 Drawing Figures US. Patent Oct. 28, 1975 Sheet10f3 3,915,231

US. Patent 'Oct.28, 1975 Sheet2of3 3,915,231

US. Patent Oct. 28, 1975 Sheet 3 of3 3,915,231

METHOD FOR DRILLING THROUGH CAVITIES DURING EARTH DRILLING OPERATIONS This invention relates to a method of drilling through cavities encountered during earth drilling operations. When drilling holes into the earth for various purposes such as geological sampling, oil prospecting and water boring, cavities are encountered from time to time and it is necessary to suspend drilling operations and to fill the cavity with concrete or other suitable material. After the cavity has been filled, the hole is drilled through the filling material into the strata below the cavity. The delays and expense occasioned by such filling operations are considerable. The object of the present invention is to provide a method of forming a bridge through the cavity in the vicinity of the hole to enable drilling operations to be continued without the necessity for filling the entire cavity and so reducing the time required.

Accordingly the invention resides in a method of drilling holes through cavities encountered during earth drilling operations which comprises stopping the drilling operation, lowering a cage down the borehole across the longitudinal direction of the cavity pouring a quick setting concrete into the hole and retarding the spreading of the concrete into the cavity by said cage so as to form a column extending across the cavity, substantially in alignment with the hole being drilled and then drilling through said column, after the concrete has set.

A suitable means for retarding the spread of the concrete into the cavity and forming the column comprises a series of rods or tubes being of such a length that the upper ends project in the drill hole partly above saidcavity and the lower ends are in contact with the bottom of the cavity, the rods being spaced apart around the periphery of the drill hole to define an enclosure into which enclosure the concrete is poured.

The rods or tubes are formed of a material which can easily be drilled such as a suitable plastic material such as polyvinyl chloride or of aluminum. The lower ends of the rods may be tied or fixed together by any suitable means, or they may be embedded into an anchoring or bedding plug which is adapted to pass through the drill hole and rest on the bottom of the cavity, or they may be fitted into any other suitable bedding or anchoring means.

The invention may be more fully understood in the light of the following description of several specific embodiments of the invention:

FIG. 1 is an elevational view of one specific form of the means for retarding the spread of the concrete;

FIG. 2 is a plan view of the means of FIG. 1;

FIG. 3 is a schematic view of the means for retarding the spread of concrete mounted in a cavity;

FIG. 4 is a similar view of FIG. 3 after the concrete has been poured into the cavity;

FIG. 5 is a side elevation of the retarding means with coil spring.

The embodiment as illustrated in FIG. 1 comprises a retarding means having rods 11 mounted in a bedding or anchoring plug 12. Rings 13 assist in supporting the rods in position such that they maintain their shape when placed in position in the cavity and during pouring. The plug is preferably formed from concentrate.

When the cavity is encountered the drill is removed and a small quantity of concrete poured into the hole to form a suitable base 14 at the bottom of the cavity. The retarding means is then lowered into the hole such that the bedding plug 12 is lowered onto the bed of concrete 14 before the concrete sets so the bedding plug is firmly anchored into position. The rods are of sufficient length to project into the drill hole above the cavity for a distance of approximately 1 to 2 feet, and in effect form a cage or enclosure with longitudinal bars extendings from the top to the bottom of the cavity in alignment with the hole. A stiff mix of quick setting concrete is then poured into the hole and into the cage or enclosure. Because it is partially retained by the rods it builds up in the column extending from the top to the bottom of the cavity as seen in FIG. 4. The weight of the concrete forces the rods to bow outwardly and some of the concrete oozes out from between the rods so that the diameter of the column 15 is somewhat greater than the diameter of the hole being drilled. When the column has been completed and the concrete sufficiently setlthe drilling operations can be resumed the hole being drilled through the column of concrete.

A difficulty arises when the bottom of the cavity is composed of loose material such as gravel. In such a situation it is difficult to firmly bed the end of the retarding means. To provide for this situation the lower end of the retarding means, as seen in FIG. 5, may be fitted with a coil spring 16, a hole is drilled into the bottom of the cavity but because of the nature of the material the hole will fill up when the drill is removed. The retarding means is then lowered into position and bounced in a vertical direction such that the coil spring embeds itself into the loose material until it is firmly fixed into position. The concrete may be then poured into the cavity.

By forming a column across the cavity in this manner the need to virtually fill the cavity is eliminated. The amount of material and time required is substantially reduced.

I claim:

1. A method of bridging a cavity encountered during earth drilling operations wherein a drill hole is drilled in communication with the cavity and the base of the cavity opposite the drill hole communication, is loose particulate material, said method comprising ceasing the drilling operation upon encountering such a cavity, lowering a bridging means down the drill hole communication and the cavity such that said bridging means extends across the cavity from the drill hole communication to the base of the cavity, said bridging means comprising a plurality of rods or tubes being fixed together at their upper and lower ends such that said rods or tubes form a substantially cylindrically shaped enclosure or cage, the length of said bridging means being such that said bridging means at least extends from the base of the cavity into the drill hole communication above the cavity, a coil .spring being mounted at said fixed lower ends of said rods or tubes with the longitudinal central axis of said coil spring being substantially coincidental with the longitudinal central axis of said bridging means, applying an intermittant downwardly and longitudinally directed force to said bridging means to cause a bouncing action on said coil spring to embed at least a portion of said coil spring in said loose particulate material, pouring concrete down said bridging means and between said rods or tubes to form a column across the cavity and in alignment with said drill hole communication, allowing the concrete to set and continuing the drilling operation by drilling through the column so formed.

2. Means for bridging a cavity encountered during earth drilling operations wherein a drill hole is drilled in communication with the cavity, said means comprising a plurality of rod like members being fixed together at their upper and lower ends such that said rod like members form a cylindrical shaped enclosure, the diameter of said enclosure being less than that of the drill hole, the length of said bridging means being sufficient to extend across the cavity and into the drill hole above the cavity, a coil spring being mounted at one end of said bridging means such that the central longitudinal axis of said coil spring is substantially coincidental with the longitudinal central axis of said bridging means.

3. Means for bridging a cavity encountered during earth drilling operations wherein a drill hole is drilled in communication with the cavity comprising a plurality of rod like members, a block of solid material having one end of said rods set therein in spaced positions to define a substantially cylindrical cage, the diameter of said block and said cage being less than the diameter of the drill hole being drilled, and the length of said rod like members being longer than the depth of the cavity to be bridged, rings slideably surrounding said rod like members whereby when concrete or like setting material is poured down the drill hole into said cage, the diameter of said cage between said rings will be increased by said concrete to a diameter greater than the drill hole being drilled. 

1. A METHOD OF BRIDGING A CAVITY ENCOUNTERED DURING EARTH DRILLING OPERATIONS WHEREIN A DRILL HOLE IS DRILLED IN COMMUMICATION WITH THE CAVITY AND THE BASE OF THE CAVITY OPPOSITE THE DRILL HOLE COMMUNICATION, IS LOOSE PARTICULATE MATERIAL, SAID METHOD COMPRISING CEASING THE DRILLING OPERATION UPON ENCOUNTERING SUCH A CAVITY, LOWERING A BRIDGING MEANS DOWN THE DRILL HOLE COMMUNICATION AND THE CAVITY SUCH THAT SAID BRIDGING MEANS EXTENDS ACROSS THE CAVITY FROM THE DRILL HOLE COMMUNICATION TO THE BASE OF THE CAVITY, SAID BRIDGING MEANS COMPRISING A PLURALITY OF RODS OR TUBES BEING FIXED TOGETHER AT THEIR UPPER AND LOWER ENDS SUCH THAT SAID RODS OR TUBS FORM A SUBSTATIALLY CYLINDRICALLY SHAPED ENCLOSURE OR CAGE, THE LENGTH OF SAID BRIDGING MEANS BEING SUCH THAT SAID BRIDGING MENS AT LEAST EXTENDS FROM THE BASE OF THE CAVITY INTO THE DRILL HOLE COMMUNICATION ABOVE THE CAVITY, A COIL SPRING BEING MOUNTED AT SAID FIXED LOWER ENDS OF SAID RODS OR TUNES WITH THE LONGITUDINAL CENTRL AXIS OF SAID COIL SPRING BEING SUBSTANTIALLY COINCIDENTAL WITH THE LONGITUDINAL CENTRAL AXIS OF SAID BRIDGING MEANS, APPLYING AN INTERMITTANT DOWNWARDLY AND LONGITUDINALLY DIRECTED FORCE TO SAID BRIDGING MEANS TO CAUSE A BOUNCING ACTION ON SAID COIL SPRING TO EMBED AT LEAST A PORTION OF SAID COIL SPRING IN SAID LOOSE PARTICULATE MATERIAL, POURING CONCRETE DOWN SAID BRIDGING MEANS AND BETWEEN SAID RODS OR TUBES TO FORM A COLUMN ACROSS THE CAVITY AND IN ALIGNMENT WITH SAID DRILL HOLE COMMUNICATION, ALLOWING THE CONCRETE TO SET AND CONTINUING THE DRILLING OPERATION BY DRILLING THROUGH THE COLUMN SO FORMED.
 2. MEANS FOR BRIDGING A CAVITY ENCOUNTERED DURING EARTH DRILLING OPERATIONS WHEREIN A DRILL HOLE IS DRILLED IN COMMUNICATION WITH THE CAVITY, SAID MEANS COMPRISING A PLURALITY OF ROD LIKE MEMBERS BEING FIXED TOGETHER AT THEIR UPPER AND LOWER ENDS SUCH THAT SAID ROD LIKE MEMBERS FORM A CYLINDRICAL SHAPED ENCLOSURE, THE DIAMETER OF SAID ENCLOSURE BEING LESS THAN THAT OF THE DRILL HOLE, THE LENGTH OF SAID BRIDGING MEANS BEING SUFFICIENT TO EXTEND ACROSS THE CAVITY AND INTO THE DRILL HOLE ABOVE THE CAVITY, A COIL SPRING BEING MOUNTED AT ONE END OF SAID BRIDGING MEANS SUCH THAT THE CENTRAL LONGITUDINAL AXIS OF SAID COIL SPRING IS SUBSTANTIALLY COINCIDENTAL WITH THE LONGITUDINAL CENTRAL AXIS OF SAID BRIDGING MEANS.
 3. Means for bridging a cavity encountered during earth drilling operations wherein a drill hole is drilled in communication with the cavity comprising a plurality of rod like members, a block of solid material having one end of said rods set therein in spaced positions to define a substantially cylindrical cage, the diameter of said block and said cage being less than the diameter of the drill hole being drilled, and the length of said rod like members being longer than the depth of the cavity to be bridged, rings slideably surrounding said rod like members whereby when concrete or like setting material is poured down the drill hole into said cage, the diameter of said cage between said rings will be increased by said concrete to a diameter greater than the drill hole being drilled. 